What happened to sep in errorrs.join

[jal...@gmail.com]

In the errors.join proposal, the proposed api had the user specify how they wanted the errors to be formatted together. But the actual implementation omitted and only used new line.

This is quite unfortunate if you are using slog and want to log that error and very much need a log statement to not span multiple lines. It also makes it much harder to read. 

Does anyone recall why sep was dropped?

Thanks,

Joe 

[Ian Lance Taylor]

See the discussion at https://go.dev/issue/53435, especially
https://github.com/golang/go/issues/53435#issuecomment-1190654775 and
https://github.com/golang/go/issues/53435#issuecomment-1190845424.

As far as the slog package it seems to me that a handler can enforce
that individual messages are on a single line. There may be a better
way to address that problem, but I don't think that errors.Join is the
right place for a fix. Any random package can generate multiline
error messages with errors.New("a\nb"), and I've seen plenty that do.
So enforcing single-line messages on errors.Join won't fix the problem
in general.

Ian

[Joseph Lorenzini]

Thanks that was very helpful. As for your point about slog, yes a custom handler could but I am using the library json handler.

I suppose the proper way to frame my problem is that I am using the slog library handler and I do not want new lines in the message or keys. 

Would the go team would be open to providing knobs to control how the handler does formatting? I assumed if I tried opening a proposal like that I’d be told to write a custom handler. :) 

[Ian Lance Taylor]

[ + jba ]

[Jonathan Amsterdam]

I think you can do what you want with `HandlerOptions.ReplaceAttr`. It is given every attribute, even the message.

It can't change the group names, though, and those can have newlines.

[Tamás Gulácsi]

Strange. AFAIK the JSON handler escapes the \n in strings.

[jal...@gmail.com]

this works fine for my purposes

https://go.dev/play/p/YSoeYS09v4O

Thanks,

Joe

[Marian Ciobanu]

Unless I'm missing something, these are equivalent:

    errors.Join(err1, err2)
    fmt.Errorf("%w\n%w", err1, err2)

So you can use the second form to achieve something similar to whatever separator you want to use.